Once you confirm salt is correct with the K1766 test I would run FC, CC, and pH daily until you have your new swg lined out. You really need all 3 readings to know what's going on with the pool. After you get to know the pool you'll be able to drop back to a couple times per week.
One of the really nice things about a salt pool is it can be almost "set it and forget it". I just test to verify a couple times per week to be sure everything's OK. I've been at constant 40% with the same runtime now for over a year. Beginning of spring FC started to drop down so I did some further testing and found CYA was way low at 30 and salt was also low. I corrected these and FC jumped right up to 8. It now runs between 6-8 depending on amount of sun, rain, swimmers etc. One of our experts, @Jimrahbe posted once that he just runs a little above target. Since he's got several pools and been doing this for years longer than me I just started doing the same thing. Works great for me too!
5 Days ago I had a small amount of FC TC difference, less than 1, I want to say it was .2 but can't recall at this time.
Today FC was 4 with a TC of 4. No CC showing on my TF-100 test.